How make visible grid cell size
Grid subdivision

You can avoid progressive subdivision of the grid by setting the Subdivision parameter to 1. The scale of the grid is in the Scale field: it's a multiplier for your current unit.

You can find the parameters in the Display panel of the Properties panel of the 3D view:





I never heard of a plugin capable of printing the coordinates of the grid. it would probably not be very easy to work with, but there are around lots of plugin/tools that can help you in measuring distances, such as:


Mesh Display Info (edge length, angle...)
Transform panel (for the global/local coordinates),
Ruler/Protractor tool
Measure-it add-on
and many other...   


See for example:  How to get selected edges length?